(a) Field of the Invention
The present invention relates to a method for detecting a victim signal in a multi-band orthogonal frequency division multiplexing ultra wideband communication system.
(b) Description of the Related Art
For the use of UWB (Ultra Wide Band) systems in a particular frequency band to protect communication systems that exist or will be introduced in the future, a technology standard regulates that other communication signal of a certain level is to be detected and measures are to be taken to protect the detected communication signal. There are no specific worldwide common standards on the type of victim signal, a victim detection level, etc. to apply such a DAA (Detect And Avoid) technology standard to an actual communication system. Also, a victim communication system to be protected, a victim detection level for applying the avoid technology to UWB, and so on are differently set according to different countries.
The detect and avoid technology standard, as discussed so far, is mainly about an avoid algorithm that sets a victim signal detection level for protecting a victim signal and is applicable according to the victim signal detection level. For example, there is an avoid algorithm that, if a packet error rate received by MAC (Medium Access Control) is higher than a reference value, discriminates whether the packet error rate comes from other UWB device or other communication equipment and then performs an interference avoiding operation.
Moreover, to prevent UWB signal interference in a WiMax band for a victim signal, an avoid algorithm is proposed which controls a band including a null tone among 128 IFFT-mapped tones of an ultra wideband signal to be shifted to a band where an interference with an WiMax signal occurs. In addition, there is an avoid algorithm in which a UWB device detects the strength of a received signal of a UWB communication band, and if the detected strength of the received signal is within a determined range of interference, determines that it has a possibility of interference with other devices and selects a different UWB communication frequency band.
To apply the detect and avoid technology standard, when a victim signal of a specific received signal level is detected from a UWB device, it is necessary for the UWB device to decrease its communication output or switch its communication band to another frequency band within a specific length of time. Typically, in order to detect such a victim signal of a specific level, the presence or absence of a victim signal of a specific level is detected, while the communication of the UWB device is being stopped, within a specific time range of avoidance defined by the detect and avoid technology standard. In this case, the communication of the UWB device has to be stopped to detect a victim signal at specific time intervals even when no victim signal is present, thus significantly lowering the throughput of the UWB communication device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.